/* 全局样式 */
body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
}

/* 导航栏样式 */
.navbar {
  background-color: #333;
  overflow: hidden;
}

.navbar ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.navbar li {
  float: left;
}

.navbar li a {
  display: block;
  color: #fff;
  text-decoration: none;
  padding: 14px 20px;
}

.navbar li a:hover {
  background-color: #575757;
}

/* 清除浮动 */
.navbar::after {
  content: "";
  display: table;
  clear: both;
}

/* 页面标题和段落 */
h1 {
  text-align: center;
  margin-top: 20px;
}

p {
  width: 80%;
  margin: 10px auto;
}

/* 主容器样式 */
.container {
  width: 60%;
  margin: 20px auto;
  height: 2000px;
}

/* 主内容区样式 */
.main-content {
  float: left;
  width: 60%;
}

.main-content img {
  max-width: 100%;
  height: auto;
}

/* 侧边栏样式 */
.sidebar {
  float: left;
  width: 28%;
  margin-left: 2%;
  background-color: #f4f4f4;
  padding: 10px;
  position: sticky;
  top: 0px;
}

.sidebar h3 {
  margin-top: 0;
}

.sidebar ul {
  list-style: none;
  padding: 0;
}

.sidebar li {
  margin-bottom: 10px;
}

.sidebar li a {
  text-decoration: none;
  color: #333;
}

.sidebar li a:hover {
  text-decoration: underline;
}

/* 清除浮动 */
.container::after {
  content: "";
  display: table;
  clear: both;
}

/* 页脚样式 */
.footer {
  background-color: #333;
  color: #fff;
  text-align: center;
  padding: 10px 0;
  margin-top: 20px;
}

/* 回到顶部按钮样式 */
.back-to-top {
  position: fixed;
  bottom: 20px;
  right: 20px;
}

.back-to-top a {
  display: block;
  background-color: #333;
  color: #fff;
  padding: 10px 15px;
  text-decoration: none;
  border-radius: 5px;
}

.back-to-top a:hover {
  background-color: #575757;
}